THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 45 



Figure 22. — Dentition of newly born male sea otter (62-178), taken at 

 Amchitka Island, 18 February 1962, weight 1.7 kg. (3.7 lb.), length 528 

 mm. The canines and one pair of upper incisors are clearly shown. The 

 barely erupted first postcanine is visible and the second postcanine is in- 

 dicated by an arrow. The young sea otter pup probably receives most of 

 its nutrition from mother's milk but soon after birth its mother gives it 

 soft bits of solid food. (KWK 62-14-28) 



The complete juvenile dentition (fig. 23), consisting of 44 

 teeth of which 26 are gingivally erupted, is obtained within about 

 the first 2 to 3 months after birth when the young otter has 

 reached a body weight of about 4 kg. (8-9 lb.). This mixed or 

 transitional dentition is retained for several months. 



The complete permanent or adult dentition (fig. 21) consisting 

 of 32 teeth is attained toward the end of the first year of life and 

 before sexual maturity is attained. 



The dental formulae given below were determined from skulls 

 that appeared to be typical of the stages of development. These 

 skulls were chosen after examining several dozen specimens. 



Dental formulae 



Figures represent the number of teeth present on one side; those in 

 parentheses are not yet gingivally erupted. Lower case=ideciduous tooth; 



